Monocytes

Julen Lux Baranano

edited by

Joshua Klemt,

1. Definition

Monocytes are a type of white blood cell (leukocyte) that belong to the innate immune system. They make up 2-8% of total leukocytes in the bloodstream and are the largest type of blood cell, typically measuring 15-20 µm in diameter.

2. Physiology

Normal Monocyte Count
- Absolute Number: 200 to 800 cells per microliter (µL) of blood
- Percentage: 2-8% of the total white blood cell (leukocyte) count
Monocytosis: elevated monocyte count exceeds 800 cells/µL
Monocytopenia: low monocyte count below 200 cells/µL

3. Function

Phagocytosis
- Engulf and digest bacteria, viruses, fungi, dead cells, and other debris
- First responders to infection or tissue injury
Differentiation
- Transform into macrophages or dendritic cells when they migrate into tissues
- Macrophages: Involved in long-term tissue repair and maintenance
- Dendritic cells: Act as antigen-presenting cells to activate T-cells
Antigen Presentation
- Present foreign antigens to T lymphocytes, activating the adaptive immune response
- Link between innate and adaptive immunity
Cytokine Production
- Secrete signaling molecules (cytokines) like IL-1, IL-6, and TNF-α
- Regulate inflammation and immune responses
Tissue Repair and Inflammation Control
- Macrophages derived from monocytes remove dead cells and promote healing
- Help modulate inflammation to prevent excessive tissue damage

4. Category

Monocytes belong to the myeloid lineage of blood cells, originating from hematopoietic stem cells in the bone marrow, and are part of the innate immune system, which provides the body with a first-line, nonspecific defense against pathogens.

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Specialty

histology, immunology, Physiology

Keywords

Last edit:

2024-12-26 19:21:44

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